1. Melissa Aromin Anesthesia Clerkship

2. Adult Circulation Fetal Circulation -RA  LA -RA  PA  Aorta

3. First breath  decrease pulm vascular resistance  increase pulm blood flow  functional FO closure Increase arterial oxygen  functional DA closure Anatomic Closure FO: months DA: 2-3 weeks Reversal of closures: -hypoxia, hypercarbia, acidosis -Increase pulm vascular resistance  open DA -Increase right heart pressure  open FO

4. Fetal Hemoglobin -Fetal  Adult hemoglobin at 2-3 months  physiological anemia -Fetal hemoglobin  left shift  decrease oxygen delivery to tissues -Increase oxygen delivery by: -Higher hemoglobin concentration -Increase CO

5. Cardiac Output Neonatal myocardium: immature contractile elements and less compliant Affect on Cardiac Output -CO = SV x HR -Fluids  little change in SV -Must increase HR to increase CO

6. Neonatal sympathetic NS and baroreceptor reflexes: immature Hypovolemia with decreased vasoconstriction -> hypovolemia without tachycardia Reduced concentration of neurotransmitter, but mature adrenergic receptors  respond better to direct-acting inotropes 10% reduction in blood volume will cause a 15-30% decrease in MAP

7. Physiological differences between neonatal and adult myocardium

8. References Swamy et al. Applied aspects of anatomy and physiology of relevance to pediatric anesthesia. Indian J. Anaesth. 2004;48(5):333-339. Brasoveanu E. Neonatal physiology and anesthesia. www.bu.edu/.../05sprgmed anesthesiology /.../ Neonatal %20 Physi ology / Neonatal %20 Physiology %20and%20 Anesthesia.doc www.bu.edu/.../05sprgmed anesthesiology /.../ Neonatal %20 Physi ology / Neonatal %20 Physiology %20and%20 Anesthesia.doc Burd et al. Neonatal and childhood perioperative considerations. Surg Clin North Am. 2006;86(2):227-247.